Recent advancement in information network leads to increasing demands for thin, lightly-weighted, and low-power-consuming display elements. Under such circumstances, a bright and low-voltage-driven organic EL (electroluminescent) display has received much attention. Particularly, research and development in recent years have remarkably improved a light emitting efficiency of an organic EL element in which an organic (high-polymer) material is used, and the organic EL display is now available for practical applications.
A hole and an electron is injected respectively from a cathode and an anode into a solid thin film containing a fluorescent organic molecule by applying an electric charge via electrodes sandwiching the solid thin film. These carriers move within the thin film due to an applied electrical field, and are recombined with each other. An energy discharged from the recombination is consumed to excite the fluorescent molecule into an singlet exited state (molecular exciton), and the organic EL element utilizes the fluorescence discharged when the singlet exciton is turned into a ground state.
In a color display, “One pixel” sometimes means a group of plural light emitting sections, such as a set of R, G, and B. However, in this specification, “one pixel” denotes one individual light emitting section.
A conventional active matrix organic EL display element (organic EL display) is described below. FIG. 36 is a longitudinal sectional view illustrating a configuration of one pixel of the conventional organic EL element. As illustrated in FIG. 36, the conventional organic EL element is provided at least with a substrate 301, a first electrode 302 provided on the substrate 301, an organic EL layer 303, and a second electrode 304.
It is preferable that barriers 305 be provided on side-edge portions of the organic EL layer 303 and the second electrode 304. Further, for the sake of contrast, it is preferable that a polarizer 307 be provided on that surface of the substrate 301 which does not face to the first electrode 302. Further, for the sake of reliability, it is preferable that a sealing film or a sealing substrate 306 be provided on the second electrode 304.
Here, the organic EL layer 303 may be a single-layered structure including only an organic light emitting layer, or a multilayered structure including a charge transport layer (electron transport layer or a hole transport layer) and the organic light emitting layer.
A photoresist method is conventionally known as a method for manufacturing the organic EL layer in the organic EL display device. In a case of using the photoresist method, a black matrix (hereinafter referred to as BM) made of a metal oxide or the like is formed on a glass substrate by photolithography and etching. Then, by using a spinner, an entire surface of the glass substrate is coated with a photosensitive resin in which a pigment of a predetermined color is dispersed. The photosensitive resin is then dried, and is subjected to exposure and development. In this way, a color pixel pattern of the predetermined color is obtained. This process is repeated three times, i.e., for each of three colors R, G, and B (Red, Blue, and Green), so as to form an organic EL pattern.
However, the foregoing method has a problem in that a previously-formed organic EL layer is easily damaged in a photolithography process for forming a successively-formed organic EL layer. Further, an organic EL material needs to be also applied to a non-desirable position. This caused a material cost to increase. Further, the photolithography process is disadvantageous in terms of production costs, because (I) production facility therefor is expensive, and (II) the photolithography process is not so flexibly adjustable to allow any change in design.
In view of that, Japanese Laid-Open Patent Application No. 10-12377/1998 (Tokukaihei 10-12377; published on Jan. 16, 1998) discloses a technique for patternizing a light emitting layer by using an inkjet method. The foregoing publication discloses a method for manufacturing an organic EL layer, in which inks of R, G, and B are respectively printed only in predetermined positions of the glass substrate, thereby forming a color pixels pattern.
With the inkjet method, it is possible to form layers for three primary colors R, G, and B simultaneously. This prevents the organic EL element from being damaged by the repeating photolithography process, and allows reduction of a production time. Further, since the ink is only applied to a position of the color pixel, an amount of the pigment used becomes less than the amount used in the photolithography method. Thus, it is possible to realize a remarkable reduction of the material cost. Further, since it is not necessary to carry out the complicate exposure and development, a developing apparatus becomes no longer necessary. Therefore, the manufacturing cost is reduced. Moreover, since it is possible to work under a normal temperature and a normal pressure, the inkjet method appears to be more promising in improving a productivity, and in simplifying the productive facility.
However, the manufacturing of the organic EL layer by using the conventional inkjet method causes the following problems.
Namely, in the conventional inkjet method, there has not been carried out a sufficient study on how to dry the droplets ejected from a nozzle. Thus, droplets do not immediately dry after landing on a substrate. This results in a greater amount of non-dried droplets on the substrate in order to obtain a desirable layer thickness of the organic EL layer. As a result, it takes long time for drying the droplets, thereby allowing the droplets to move on the substrate before the droplets dry. This deteriorate a formation accuracy of the organic EL layer.
In order to solve the foregoing problem, there is a method in which a landed droplet is positionwise restricted by forming a liquid-affinitive region and a liquid-repellent region on a top surface of the substrate. In this case where the liquid-affinitive region and liquid-repellent region are formed, the organic EL layer is formed by a formation method as described hereinbelow with reference to FIGS. 37(a) to 37(c).
First, a liquid-affinity treatment is carried out with respect to the entire surface of a substrate 311. Then, a liquid-repellent region 313 is formed by carrying out the photolithography process, the liquid-repellent region 313 having a line width of 10 μm between pixels adjacent to each other, where a size of one pixel is 120 μm×100 μm by way of example. In this way, a liquid-affinitive region 312 and the liquid-repellent region 313 are segmented from each other as illustrated in FIG. 37(a).
Next, an ink droplet 314 is ejected toward the liquid-affinitive region 312. The droplet 314 landed on the substrate 311 does not spread out in the liquid-repellent region 313, and is retained in the liquid-affinitive region 312. Then, a solvent of the droplet 314 is dried off, thereby forming the organic EL layer.
The foregoing method, however, has the following problems.
For example, in a case where a thickness of the organic EL layer is 0.05 μm and a volumetric concentration of the ink is 0.1%, a size of a single droplet is 105 μm. The droplet 314 is extended by 1.5 times of a diameter thereof due to an impact caused by landing on the substrate 311. Therefore, as illustrated in FIG. 37(b), a part of the landed droplet 314 is spread out beyond the liquid-repellent region 313 (that serves as an external frame of the pixel), and reaches the liquid-affinitive region 312 of the next pixel. If the ink which is a part of the landed droplet 314 moves to the other liquid-affinitive region 312 before the droplet 314 dries, the ink will not return to the pixel (liquid-affinitive region 312) on which the droplet 314 originally has landed. This causes the droplet 314 to split as illustrated in FIG. 37(c).
Reduction of the diameter of the single droplet is an option to avoid the foregoing problem. For example, in a case where:(pixel width 100 μm)+(external frames on both edges 10 μm×2)=120 μm,the diameter of the droplet (ink) 314 ejected from the nozzle is determined as 120÷1.5=80 μm, in order to retain the droplet 314 within the liquid-affinitive region 312 immediately after the landing.
In this case, the thickness of the organic EL layer formed by the single droplet 314 is 0.02 μm. This is less than a half of the desirable thickness. Therefore, the droplet 314 needs to be ejected toward the same pixel twice or more. However, after a first droplet, successive droplets land on the organic EL layer formed by a previously landed droplet. Since the organic EL layer formed by the previously landed droplet is not subjected to the liquid-affinity treatment,.the successive droplets do not spread out in a desirable shape. This causes an unevenness. Further, if the successive droplets land before the previous droplet dries, the ink will spread out to the liquid-affinitive region 312 of the next pixel. Therefore, ejection of the successive droplets must be suspended until the previous droplet 314 dries. This results in a poor productivity. Further, it is necessary to carry out the photolithography process for forming the liquid-affinitive region and the liquid-repellent region. This does not allow the inkjet apparatus to contribute to simplification of the productive facility advantageously.
Further, in order to solve the foregoing problems, an option is to form a barrier around the pixel so as to prevent the ink to spread out beyond the barrier. A method for forming the organic EL layer using such a technique is described with reference to FIGS. 38 and 39.
On the substrate 311 of the organic EL display, a black matrix (Hereinafter referred to as BM) is formed for obtaining a clear contrast of the pixels. It is suggested that this BM be used as a barrier for blocking the spreading-out of the droplet 314 containing the organic EL material (FIG. 38(a)).
However, as illustrated in FIG. 38(b), the foregoing method of utilizing the barrier 315 causes the uneven thickness of the organic EL layer 316 formed after the droplet 314 dries. In this case, the organic EL layer 316 is thin at its central portion and thick at a portion along the barrier 315. This uneven thickness must be avoided, because it largely affects a color property of the organic EL display. In view of that, it is suggested that a liquid-repellency treatment be carried out with respect to the barrier 315 in order to avoid an adhesion of the ink to the barrier 315. The method, however, does not yet solve the problem of the depression at the center portion.
Further, the method using the barrier 315 also has the following problems.
In forming the organic EL layer of a desirable thickness, the droplet 314 should contain the organic EL material of a volume corresponding to (1 pixel area×thickness), the organic EL material dissolved in the droplet 314. For example, in one pixel of the organic EL display device, a size of a display region is 120 μm×100 μm, and the thickness of the substrate 311 is 0.05 μm. In order to form these dimensions with a single droplet, the diameter of the droplet is required to be 105 μm where it is supposed that the volumetric concentration of the organic EL material is 0.1%. Therefore, a height of the BM (barrier 315) needs to be 1000 times of the thickness of the organic EL layer. This not only causes waste of the BM material, but also affects an overall design of an organic EL display apparatus.
In a meanwhile, the foregoing problem is not solved by merely reducing the diameter of the droplet, if the levels of the BM and the organic EL layer is kept equal to each other. First, to arrange the size of the droplet to be so small that the droplet does not flow out of the barrier 315 as illustrated in FIG. 39(a), the size of the single droplet must be reduced to 10 μm. However, in a conventional inkjet method, the droplet of a smaller size is more largely affected by an air resistance while it is flying in the air. Therefore, a flying speed of the droplet slows down, and a landing accuracy is deteriorated. Further, a volume of an unfilled portion within the barrier 315 decreases as a solute content of the previous droplet 314 (previous-droplet-substance 317 to be cured) is deposited on a bottom portion within the barrier 315. This causes the droplet landing afterward to flow out of the barrier 315 as illustrated in FIG. 39(b).
To solve this problem, one option is to increase concentration of the droplet 314, and eject the droplets 314 at sufficiently long intervals, so that the solvent of the previous droplets is dried off by the time a final droplet is landed. However, the higher the concentration of the droplet becomes, the higher viscosity the ink has so as to be unable to be ejected by using a conventional inkjet method. Further, it is necessary to carry out the photolithography process for forming the BM. Therefore, the inkjet apparatus is not allowed to contribute to simplification of the productive facility advantageously.
Further, a liquid crystal array is conventionally manufactured by the following manufacturing process. First, on one of a pair of transparent glass substrates, a liquid crystal driving element, such as a TFT (thin film Transistor) is formed. Then, a transparent electrode and an alignment film are formed and spacers are applied on the one of the substrates. Next, this substrate is assembled together with another substrate on which a colored color filter, a transparent electrode and an alignment film are formed. Then, liquid crystal is injected into a gap formed by the spacers between the substrates, and the substrates are sealed off.
In this manufacturing method, silica or plastic particles of several micrometers are usually spread out as the foregoing spacers.
However, in this manufacturing method, the spacers are placed also in aperture areas (region for controlling transmission and reflection of light) of the liquid crystal array. Further, the spacers are placed unevenly in terms of its number and position. This causes the aperture ratio to decrease, thereby resulting in a poor displaying quality or an uneven display.
In order to avoid the decrease in the aperture ratio, it is suggested that by using an inkjet apparatus, spacers are arranged and formed on a black matrix (BM) of a color filter substrate.
For example, Japanese Laid-Open Patent Application No. 281562/1993 (Tokukaihei 5-281562; published on Oct. 29, 1993) discloses a method in which liquid crystal mixed with a spacer material is (A) heated by using a heater and stirred by using a stirring device at the same time, and (B) ejected toward a liquid crystal substrate by using an inkjet apparatus having a nozzle of 60 μm in nozzle diameter. In this method, the ejection of the liquid crystal by using the inkjet method is made possible by heating the liquid crystal so as to lower viscosity of the liquid crystal. This allows the spacer material to be evenly spread out immediately when the liquid crystal is dropped.
Further, in a method disclosed in Japanese Laid-Open Patent Application No. 2001-42338 (Tokukai 2001-42338; published on Feb. 16, 2001), the spacers are formed by (I) plotting a spacer pattern by using the inkjet method for applying, on a substrate, a spacer forming material in a form of ink, and (II) curing the spacer forming material.
However, the method for forming the spacer by using the conventional inkjet apparatus has the following problem.
In a case where the spacer pattern is plotted by drying the spacer forming material applied by using the inkjet method, a higher concentration of the spacer forming material causes a higher viscosity of the spacer forming material.
Typical inkjet methods such as a bubble-jet method or a piezo-electric method are usually arranged such that a viscosity of a substance that can be ejected is about 2 to 20 Pc and a substance having a viscosity higher than this range cannot be ejected therefrom.
Further, it is suggested that the viscosity of the ink to be ejected is decreased by heating a vicinity of the nozzle. However, in this method, the spacer forming material may be cured within the nozzle and clog the nozzle, in a case where a curable resin is used as the spacer material.
On the contrary, in order to eject the spacer material without heating the vicinity of the nozzle, it is necessary to increase an amount of the solvent so as to decrease the viscosity of the spacer forming material. This lowers the concentration of the spacer forming material. For example, in the conventional method, the spacer forming material includes 10 wt % of copolymer, 80 wt % of water, and 10 wt % of ethylene glycol. After the spacer forming material is dried, a volume of the spacer forming material becomes a fraction of an original volume thereof.
Accordingly, in order to obtain the spacer of a predetermined thickness, it is necessary to enlarge the diameter of the droplet being ejected. In this case, shapes of the spacers being formed is, for example, a flat shape of 5 μm in thickness, and 50 μm in diameter. As a result, the problem of the spacer-caused decrease in the aperture ratio is not solved. Further, due to the low concentration, it is necessary to carry out baking at 100° C. for 15 min., then at 200° C. for 30 min. Therefore, it takes longer time to form the spacer.
Further, after the droplet containing the spacer material lands on the ink substrate, the droplet moves before the solvent is dried off. Therefore, the spacers are not formed in a desirable position.
Regarding this problem, an arrangement is discussed below in which the spacers are formed on the BM so as to avoid, in particular, reduction of the aperture ratio.
For example, it is supposed that a needed thickness of the spacer for the BM of 10 μm in width is 5 μm, and that the concentration of the spacer forming material (ink) is allowed to be as high as 50%. It is further supposed that the liquid-repellency treatment is carried out with respect to a surface of the BM, and that, after the droplet of the liquid lands, the droplet is not spread out, and an area of the liquid is maintained to be within 1.5 times of the diameter of the droplet.
In this case, the droplet can be as large as φ6.7 μm. However, the thickness of the spacer material remaining after the solvent is dried off is 1 μm, and is below the targeted thickness. Accordingly, it is necessary to laminate the spacer material by carrying out repeated ejections. In this case, the solvent of the previous droplet must be completely dried off before the successive droplet is ejected, otherwise the droplet will be spread out. As a result, in repeated ejection, ejection intervals (time intervals between ejections) becomes long, and a working efficiency is deteriorated.
Therefore, the concentration of the spacer forming material (ink) needs to be even higher, and a configuration capable of ejecting a droplet of such a highly concentrated spacer forming material (ink) is required.
In view of the foregoing problem, Japanese Laid-Open Patent Application No. 2000-246887 (Tokukai 2000-246887; published on Sep. 12, 2000) discloses the following technology. Namely, the foregoing application discloses a method for ejecting a highly viscous substance by using a dispenser. In the method, an electrode is arranged entirely or partially on a container in which a highly viscous substance of 100 cps to 1,000,000 cps is filled in. This container has, at its bottom section, a polygonal or circular orifice of 50 μm to 1 mm in diameter. From the orifice, the highly viscous substance is protruded out forming a meniscus. Then, the highly viscous substance protruded forming the meniscus is pulled out by applying a voltage to the electrode. Next, a part of the substance is cut off to separate, and is adhered to a medium.
This technology utilizes a fact that the meniscus from the nozzle forms a conical shape with an application of a voltage. In this case, a larger pulse amplitude forms a higher conical-shape of the meniscus. Therefore, the larger pulse amplitude increases a volume of that portion of the meniscus which is extended toward a substrate and is to touch the substrate, and thus attains a larger dot diameter.
However, in the foregoing conventional method, in a case where a desirable dot diameter is small, it is necessary to control the meniscus so that only a leading edge portion of the meniscus cone touches the substrate side. Particularly, in a case where the spacers are formed by laminating the spacer forming material (ink), a distance between a recording-subjected side member and the nozzle gradually becomes shorter, as the spacers are being laminated. Therefore, controlling of the dot diameter becomes very difficult. Further, as to stabilizing an amount of the ink being applied, it is necessary to enlarge the pulse so that not only the leading edge of the conical-shape meniscus but also a vicinity of a middle of the meniscus is abutted against the substrate. Therefore, the diameter of the droplet should be at least a half of the diameter of the nozzle or more.
In order to reduce the dot diameter in this situation, the diameter of the nozzle must be reduced. However, in this case, the nozzle-to-substrate distance must be shortened at the same time. This causes larger influences from errors in the nozzle-to-substrate distance, caused by the uneven thickness of the substrate or a wavy shape of the substrate. Thus a stable ejection becomes difficult. Recent advancement in information network leads to increasing demands for a thin, lightly-weighted, and low-power-consuming display element. Under such circumstances, a bright and low-voltage-driven liquid crystal display has received much attention.
Among those, a color liquid crystal display is so arranged that a transmission amount of light emitted from a backlight is controlled by controlling alignment of liquid crystal by using a transparent electrode (ITO film) connected to a TFT. In such a color liquid crystal display, passing of the light through a color filter causes a color to appear.
In the color display, “one pixel” sometimes means a group of plural color filters, such as a set of R, G, and B. However, in this specification, “one pixel” denotes one color filter.
Conventionally, spin-coat method has been known as one of method for manufacturing a color filter substrate. In a case of using the spin coat method, a black matrix (Hereinafter referred to as BM) made of a metal such as chrome is formed on a glass substrate by photolithography and etching. Then, by using a spinner, an entire surface of the glass substrate is coated with a photosensitive resin in which a pigment of a predetermined color is dispersed. The photosensitive resin is then dried, and is subjected to exposure and development. In this way, a color pixel pattern of the predetermined color is obtained. This process is repeated three times, i.e., for each of three colors R, G, and B (Red, Blue, and Green), so as to form a color filter pattern.
However, a color filter material needs to be also applied to a non-desirable position. This caused a material cost to increase. Further, the photolithography process is disadvantageous in terms of production costs, because (I) productive facility therefor is expensive, and (II) the photolithography process is not so flexibly adjustable to allow any change in design.
In view of that, Japanese Laid-Open Patent Application No. 75205/1984 (Tokukaisho 59-75205; published on Apr. 27, 1984) discloses a technique for patternizing a color filter by using the inkjet method. The technology relates to a method for manufacturing the color filter substrate, in which inks of R, G, and B are respectively printed only in predetermined positions of the glass substrate, thereby forming the color pixels.
With the inkjet method, it is possible to form layers for three primary colors R, G, and B simultaneously. Therefore, it is possible to reduce the production time. Further, since the ink is only applied to a position of the color pixel, an amount of the pigment used becomes less than the amount used in the spin coat method. Thus, it is possible to realize a remarkable reduction of the material cost. Further, since it is not necessary to carry out the complicate exposure and development, a developing apparatus becomes no longer necessary. Therefore, the manufacturing cost is reduced. Moreover, since it is possible to work under a normal temperature and a normal pressure, the inkjet method appears to be more promising in improving the productivity, and in simplifying the productive facility.
Further, in the foregoing application of Tokukaisho 59-75205, a dispersion preventing pattern is formed on a substrate, by using a substance having a poor wettability. On this substrate, ink containing the pigment is applied by using the inkjet method, thereby forming the color filter.
However, the manufacturing of the color filter by using the conventional inkjet method has the following problems.
Namely, there has not been carried out a sufficient study on how to dry the droplets ejected from a nozzle. Thus, droplets do not immediately dry after landing on a substrate. Accordingly, This results in a greater amount of non-dried droplets on the substrate in order to obtain a desirable layer thickness of a color filter layer. As a result, it takes long time for drying the droplets, and the droplets move on the substrate before the droplets dry. This deteriorate a formation accuracy of the color filter.
In order to solve the foregoing problem, there is a method in which a position of a landed droplet is restricted in positionwise by forming a liquid-affinitive region and a liquid-repellent region on a top surface of the substrate. In this case where the liquid-affinitive region and liquid-repellent region are formed, the color filter layer is formed by a formation method as described hereinbelow with reference to FIGS. 37(a) to 37(c).
First, a liquid-affinity treatment is carried out with respect to the entire surface of a substrate 311. Then, a liquid-repellent region 313 is formed by carrying out the photolithography process, the liquid-repellent region 313 having a line width of 10 μm between pixels adjacent to each other, where a size of one pixel is 300 μm x 100 μm by way of example. In this way, a liquid-affinitive region 312 and the liquid-repellent region 313 are segmented from each other as illustrated in FIG. 37(a).
Next, an ink droplet 314 is ejected toward the liquid-affinitive region 312. The droplet 314 landed on the substrate 311 does not spread out in the liquid-repellent region 313, and is retained in the liquid-affinitive region 312. Then, a solvent of the droplet 314 is dried off, thereby forming the color filter layer.
However, this method has the following problems.
For example, in a case where a thickness of the color filter layer is 1 μm, and a volumetric concentration of the ink is 5%, a size of a single droplet is 105 μm. The droplet 314 is extended by 1.5 times of a diameter thereof due to an impact caused by landing on the substrate 311. Therefore, as illustrated in FIG. 37(b), a part of the landed droplet 314 is spread out beyond the liquid-repellent region 313 (that serving as an external frame of the pixel), and reaches the liquid-affinitive region 312 of the next pixel. If the ink which is a part of the landed droplet 314 moves to the other liquid-affinitive region 312 before the droplet 314 dries, the ink will not return to the pixel (liquid-affinitive region 312) on which the droplet 314 originally has landed. This causes the droplet 314 to split as illustrated in FIG. 37(c).
Reduction of the diameter of the single droplet is an option to avoid the foregoing problem. For example, in a case where:(pixel width 100 μm)+(external frames on both edges 10 μm×2)=120 μm,the diameter of the droplet (ink) 314 ejected from the nozzle is determined as 120÷1.5=80 μm, in order to retain the droplet 314 within the liquid-affinitive region 312 immediately after the landing.
In this case, the thickness of the color filter layer formed by the single droplet 314 is 0.45 μm. This is less than a half of the desirable thickness. Therefore, the droplet 314 needs to be ejected toward the same pixel twice or more. However, after a first droplet, successive droplets land on the color filter layer formed by a previously landed droplet. Since the color filter layer formed by the previously landed droplet is not subjected to the liquid-affinity treatment, the successive droplets do not spread out in a desirable shape. This causes an uneven thickness. Further, if the successive droplets land before the previous droplet dries, the ink will spread out to the liquid-affinitive region of the next pixel. Therefore, ejection of the successive droplets must be suspended until the previous droplet 121 dries. This causes a poor productivity. Further, it is necessary to carry out the photolithography process for forming the liquid-affinitive region and the liquid-repellent region. This does not allow the inkjet apparatus to contribute to simplification of the productive facility advantageously.
Further, in order to solve the foregoing problems, an option is to form a barrier around the pixel so as to prevent the ink to spread out beyond the barrier. A method for forming the color filter layer using the technique is described with reference to FIGS. 38 and 39.
On a color filter substrate 1 of a liquid crystal element, a black matrix (Hereinafter referred to as BM) is formed for obtaining a clear contrast of the pixels. It is suggested that this BM be used as the barrier 315 for blocking the spreading-out of the droplet 314 containing the color filter material (FIG. 38(a)).
However, as illustrated in FIG. 38(b), the foregoing method of utilizing the barrier 315 causes the uneven thickness of the color filter layer 316 formed after the droplet 314 dries. In this case, the color filter layer 316 is thin at its central portion, and the color filter layer 316 is thick at a portion along the barrier 315. This uneven thickness must be avoided, because it largely affects a color developing property of the color filter layer 316. In view of that, it is suggested that a liquid-repellency treatment be carried out with respect to the barrier 315 in order to avoid an adhesion of the ink to the barrier 315. The method, however, does not yet solve the problem of the depression at the center portion.
Further, the method using the barrier 315 also has the following problems.
In forming the color filter layer of a desirable thickness, the droplet 314 should contain the color filter material of a volume corresponding to (1 pixel area×thickness), the color filter material dissolved in the droplet 314. For example, in one pixel of the color filter layer of the color filter substrate 311, a size of a display region is 300 μm×100 μm, and the thickness of the color filter layer is 1 μm. In order to form this by the single droplet, the diameter of the droplet is required to be 105 μm where the volumetric concentration of the color filter material is 5%. Therefore, a height of the BM (barrier 315) needs to be 20 times of the thickness of the color filter layer. This not only causes waste of the BM material, but also affects an overall design of a liquid crystal element.
In a meanwhile, the foregoing problem is not solved by merely reducing the diameter of the droplet, if the levels of the BM and the color filter layer is kept equal to each other. First, to arrange the size of the droplet to be so small that the droplet does not flow out of the barrier 315 as illustrated in FIG. 39(a), the size of the single droplet must be reduced to 20 μm. However; in a conventional inkjet method, the droplet of a smaller size is more largely affected by an air resistance while it is flying in the air. Therefore, a flying speed of the droplet slows down, and a landing accuracy is deteriorated. Further, as illustrated in FIG. 39(b), a volume of an unfilled portion within the barrier 315 decreases as a dissolved substance of the previous droplet 314 (previous-droplet-substance 317 to be cure) is deposited on a bottom portion within the barrier 315. This causes the droplet landing afterward to flow out of the barrier 315.
To solve this problem, one option is to increase the concentration of the droplet 314, and eject the droplet 314 at sufficiently long intervals, so that the solvent of the previous droplets dry by the time a final droplet is landed. However, the higher the concentration of the droplet becomes, the higher viscosity the ink has so as to be unable to be ejected by using a conventional inkjet method. Further, it is necessary to carry out the photolithography process for forming the BM. Therefore, the inkjet apparatus is not allowed to contribute to simplification of the productive facility advantageously.
(Patent Document 1)
    Tokukaihei 10-12377; published on Jan. 16, 1998)(Patent Document 2)    Tokukaihei 8-238774; published on Sep. 17, 1996)(Patent Document 3)    Tokukai 2000-127410; published on May 5, 2000)(Patent Document 4)    Tokukaihei 5-281562; published on Oct. 29, 1993)(Patent Document 5)    Tokukai 2001-42338; published on Feb. 16, 2001)(Patent Document 6)    Tokukai 2000-246887; published on Sep. 12, 2000)(Patent Document 7)    Tokukaishou 59-75205; published on Apr. 27, 1984)
Accordingly, an object of the present invention is to provide an active matrix organic EL display element, and an active matrix organic EL display element manufacturing method, for forming an organic EL layer, in which a drying rate of a landed droplet is taken into account, so that the organic EL layer is formed in an accurate position, and advantages of an inkjet method is utilized, without particular needs of a barrier, a liquid-repellent region, and a liquid-affinitive region around the pixel.
Further, the present invention is made for solving the foregoing problems, and it is also an object of the present invention to provide a liquid crystal array and a liquid crystal array manufacturing method utilizing an arrangement that allows accurate application and formation of spacers, for example, boundary between aperture sections on a substrate (such as a TFT substrate, a color filter substrate, or the like) having the aperture sections per pixel. The method of the present invention prevents spacer-caused decrease in an aperture ratio and easily obtains the spacers having desirable thicknesses (heights).
Accordingly, an object of the present invention is to provide a color filter substrate, and a color filter substrate manufacturing method, for forming a color filter, in which a drying rate of a landed droplet is taken into account, so that the color filter is formed in an accurate position, and advantages of an inkjet method is utilized, without particular needs of a barrier, a liquid-repellent region, and a liquid-affinitive region around the pixel.